Conventional fluidic systems traditionally employ a source of clean, dry pressurized air, such as filtered and dried shop air, which is also reduced to a pressure appropriate for use in the fluidic devices of the system by a pneumatic-mechanical pressure regulator. However, because the fluidic devices of the system are free of moving parts and have service lives of indefinite length, while the pneumatic-mechanical pressure regulator has both moving parts and an elastomeric diaphragm, the system reliability is compromised by the comparatively short life of the pressure regulator.
Accordingly, a long-recognized need in the fluidics art has been for the provision of a fluidic pressure regulator which is free of moving parts, and has a service life favorably comparable to other fluidic elements.
A conventional hybrid fluidic/mechanical pressure regulator is known in accord with U.S. Pat. No. 3,473,545, issued Oct. 21, 1969 to G.I. Boyadjieff, wherein a jet pressurization amplifier is employed in combination with a vortex amplifier and a diaphragm-operated poppet valve to define a pressure regulator. However, the pressure regulator taught by the `545 patent is believed to suffer from precisely the shortcomings of pneumatic-mechanical pressure regulators outlined above.
Another conventional pressure regulator which is all fluidic is known in accord with U.S. Pat. No. 3,335,737, issued Aug. 15, 1967 to W.F. Gesell, wherein a proportional fluidic amplifier has a fixed orifice on one control port in opposition to a variable orifice on the other control port with both control ports communicating with the unregulated supply pressure. One of the outlet legs is vented, while the other outlet leg provides an allegedly regulated fluid pressure. A feedback channel controlled by a fixed orifice extends from the outlet conveying regulated pressure to a feedback control port disposed in parallel with the other control port having the variable orifice. The Gesell teaching is believed to suffer from several deficiencies including non-constant output pressure with varying inlet pressure, and a relatively narrow regulation range as a function of inlet pressure.
A fluidic control system for a turbine engine is known from U.S. Pat. No. 3,682,192 issued Aug. 1972, to G. E. Davies, wherein a ratiometric relationship is established between two sources of pressurized air, and the resulting ratioed pressure signal is employed to drive a venturi tube. The output pressure signal from the venturi tube in opposition to the pressure of one of the sources of pressurized air is employed to switch a bistable fluidic valve controlling an output actuator. The device taught by Davies displays a considerable hysteresis and nonlinearity which limits its applicability.